A vinylidene fluoride resin is excellent in chemical resistance, weather resistance, resistance to contamination, etc., and is used as a molding material for various films or sheets, or a coating material, and a binder base. Moreover, since a sheet thereof is excellent also in oil-permeation resistance in addition to the outstanding weather resistance and oil resistance, there have been made some proposals of laminating it with another thermoplastic resin, such as polyamide resin or polyolefin resin, to form a tube for fuel oil supply from a gasoline tank to an engine of a car, as one of the weight-saving means of a car (Patent documents 1-4). The lamination structure is adopted in order to harmonize the excellent oil resistance and oil-permeation resistance of the vinylidene fluoride resin, and the excellent mechanical property of such another thermoplastic resin.
However, fluorine-containing resins including vinylidene fluoride resin are deficient in adhesiveness with other thermoplastic resins as is understood also from their outstanding resistance to soiling. For this reason, in the above-mentioned prior art, there have been adopted various means, such as the surface treatment of a fluorine-containing resin (Patent document 1), the insertion of an adhesive layer (Patent document 2), and the surface treatment of a fluorine-containing resin by grafting with maleic anhydride under irradiation with gamma rays (Patent documents 3 and 4), but it is hard to say that a sufficient adhesiveness is attained thereby.
On the other hand, in order to provide an improved adhesiveness with a metal or a powdery electrode material, there have been also proposed a copolymer of vinylidene fluoride with maleic anhydride, etc. (Patent document 5) and a copolymer of vinylidene fluoride with a monoester of unsaturated dibasic acid (Patent document 6). However, these vinylidene fluoride copolymers have been developed in order to form a paint, an adhesive or a binder in a solution state, and extrusion sheet formation thereof is not contemplated at all, so that it is hard to say that they are, in fact, generally suitable for sheet extrusion.                [Patent document 1] JP-A 6-31877        [Patent document 2] JP-A 6-15790        [Patent document 3] JP-A 2005-162330        [Patent document 4] JP-A 2005-207582        [Patent document 5] JP-A 62-260806        [Patent document 6] JP-A 6-172452        